The present invention relates to cartridge valve assemblies, and more particularly, to such cartridge valve assemblies requiring manual actuation.
Many off-highway vehicles, including but not limited to boom lift trucks, have a hydraulic system which includes one or more ancillary or auxiliary hydraulic functions, such as raising or lowering a boom, or extending or retracting a boom, to control some portion of the vehicle. Many of these same vehicles require that the actuation of these hydraulic functions be manual. As a result of this manual actuation requirement, two types of manually actuated valve assemblies are typically used, a manually actuated sectional valve or a manually actuated rotary cartridge valve (hereinafter referred to as a “rotary valve”).
A manually actuated sectional valve is shown in U.S. Pat. Nos. 3,434,390 and 4,011,891. This type of valve typically comprises a cast iron valve body and a spool valve. The spool valve, which extends through the entire length of the valve body, is manually actuated by a lever or handle which pivots about an axis that is rigidly attached to the valve body. The spool valve in the sectional valve interfaces directly with the spool bore defined by the valve body to control the flow of fluid to or from the auxiliary or ancillary hydraulic functions. Manual actuation of the lever results in axial (or linear) translation of the spool valve within the spool bore. While this design has proven to be very successful commercially and to work very well in many hydraulic applications, some applications require a design that is more customizable with regard to port locations. Because the valve body in the typical sectional valve is cast, the locations of the inlet and outlet ports, as well as any other ports, such as first and second actuator ports, are restricted to the port boss locations on the valve body casting. If a manufacturer of a hydraulic application requires different port locations for a particular application, a new valve body would need to be cast. However, a new casting can be cost prohibitive if the volumes of sectional valves required are not very large.
Rotary valves typically comprise a spool valve within a sleeve valve, with the sleeve valve being fixedly disposed in a valve housing. These valves also include a handle or knob which is rigidly connected to the spool valve. Actuation of these rotary valves is accomplished by rotating the handle about an axis which is coaxial to the axis of the spool valve. As is well known to those skilled in the art, rotation of the handle about the axis which is coaxial to the axis of the spool valve results in rotation of the spool valve about the axis of the spool valve. For hydraulic applications requiring greater customization with regard to port locations, many manufacturers of those applications will use rotary actuated cartridge valves. Unlike manually actuated sectional valves, the valve housing surrounding the rotary valve is typically machined from a block of aluminum or steel. Because of the relatively low manufacturing costs associated with machined valve housings, the customization issues that some manufacturers of hydraulic applications have with sectional valves are not a problem in the case of rotary valves.
However, although rotary valves have proven to be successful commercially and to work well in many applications, such valves have some disadvantages when used in certain commercial applications. One disadvantage associated with rotary valves concerns the flow rate through the valve. Because of the rotary actuation, rotary valves have a lower flow rate as compared to linearly actuated valves of a comparable size. The reason for this lower flow rate is that linear actuation of a valve allows for more fluid passage openings in the valve than rotary actuation allows.
In addition, a recent trend in commercial applications is to require that hydraulic components used on those applications, wherein the component includes a manually actuated valve assembly, be compact. Rotary valves, however, do not offer the most compact arrangement when multiple valves are used, because of the rotary actuation of the valve. When multiple rotary valves are arranged in a valve housing, adequate space must be provided between the valves to allow for manual actuation of each valve individually. Typically, the handles of valves of this type include a lever that extends radially from the rotational axis of the handles. As is well known to those skilled in the art, the lever provides a mechanical advantage in overcoming any pressure forces acting internally to the cartridge valve that make rotation difficult. The rotary valves must be spaced so that a lever on a given valve does not intrude upon the space required for full actuation of the lever of the adjacent valve. In other words, the valves must be spaced so that movement of the lever of a first valve does not result in that lever “bumping into” the lever of an adjacent valve, preventing the full range of motion of the lever of the first valve.